Transceiver systems, both wired and wireless, are used in a variety of consumer electronics, medical devices, automotive electronics, and other applications where reduced form factor and reduced cost are driving motivations. Of course, regardless of the application, a high signal-to-noise (SNR) ratio is desired, which requires a high fundamental signal to harmonic ratio.
In certain applications, a transceiver will not meet Federal Communications Commission (FCC) requirements (e.g., spectral mask requirements) if there is too much harmonic content in the output wave form. Conventionally, in order to achieve harmonic rejection levels of 40 dBc or better, significant filtering is applied using either on-chip or off-chip components, which require calibration and trimming, and consume area. Further, the use of multi-order filters may be required to achieve acceptably high harmonic filtering levels, which also consume both area and power, which is disadvantageous in any application where form factor and cost are considerations.